Undersea sand filter for cleaning injection water

Abstract

A submarine sand filter is employed to filter water for uses requiring lack of solid contaminants, such as oil reservoir injection. The filter is provided with backwash means and allows an efficient use of differential pressure heads.

I claim: 
     
       1. A method for filtering injection water prior to use in an offshore oil platform comprising filtering said water through an apparatus submerged in an ocean environment, said apparatus comprising (a) an inner chamber having an outer wall;   (b) an outer chamber surrounding said inner chamber and having an outer wall, the inner wall of said outer chamber being common with said outer wall of said inner chamber, both inner and outer walls being vertically aligned frusto-conical members set at opposing angles;   (c) means for retaining particulate filter media means in said outer chamber, said retaining means allowing fluid communication from said fluid through said retaining particulare filter media means into said inner chamber, said means being the inner and outer chamber walls comprised of vertically aligned frusto-conical members set at opposing angles, and wherein both inner and outer chambers have fluid impermeable partitions at the upper and lower ends, and wherein output means are in fluid communication with the inner chamber; and   (d) means for recovering particulate free fluid from said inner chamber.   
     
     
       2. A method as described in claim 1 wherein fluid is forced through the filter by a pump on the clean water side of the filter, and wherein the pump is submerged in the fluid at a depth sufficient to provide a pressure head to the filter. 
     
     
       3. An apparatus for removing particulate solids from fluids when said apparatus is submerged in said fluid, comprising (a) an inner chamber having an outer wall;   (b) an outer chamber surrounding said inner chamber and having an outer wall, the inner wall of said outer chamber being common with said outer wall of said inner chamber, both inner and outer walls being vertically aligned frusto-conical members set at opposing angles;   (c) means for retaining particulate filter media means in said outer chamber, said retaining means allowing fluid communication from said fluid through said retained particulate filter media means into said inner chamber, said means being the inner and outer chamber walls comprised of vertically aligned frusto-conical members set at opposing angles, and wherein both inner and outer chambers have fluid impermeable partitions at the upper and lower ends, and wherein output means are in fluid communication with the inner chamber;   (d) a cylindrical portion in axial alignment with said fluid impermeable end portions of the inner and outer chambers, said cylindrical portion penetrating the lower end of said inner chamber fluid impermeable housing, and the upper fluid impermeable ends of both the inner and outer chambers, said cylindrical portion surrounded by a housing affixed to the upper fluid impermeable end of said outer chamber, said housing containing a baffle situated over the upper end of the cylindrical portion, the interior of the housing in fluid communication with the outer chamber at the lower end and open to a three-way switching valve at the upper end;   (e) means for recovering particulate free fluid from said inner chamber.   
     
     
       4. An apparatus for removing particulate solids from fluids when said apparatus is submerged in said fluid, comprising, (a) an inner chamber having an outer wall;   (b) an outer chamber surrounding said inner chamber and having an outer wall, the inner wall of said outer chamber being common with said outer wall of said inner chamber, both inner and outer walls being vertically aligned frusto-conical members set as opposing angles;   (c) means for retaining particulate filter media means in said outer chamber, said retaining means allowing fluid communication from said fluid through said retained particulate filter media means into said inner chamber, said means being the inner and outer chamber walls comprised of vertically aligned frusto-conical members set at opposing angles, and wherein both inner and outer chambers have fluid impermeable partitions at the upper and lower ends, and wherein output means are in fluid communication with the inner chamber;   (d) a cylindrical portion in axial alignment with said fluid impermeable end portions of the inner and outer chambers, said cylindrical portion penetrating the lower end of said inner chamber fluid impermeable housing, and the upper fluid impermeable ends of both the inner and outer chambers, said cylindrical portion surrounded by a housing affixed to the upper fluid impermeable end of said outer chamber, said housing containing a baffle situated over the upper end of the cylindrical portion, the interior of the housing in fluid communication with the outer chamber at the lower end and open to a three-way switching valve at the upper end, said valve containing a first means capable of directing filtered fluid to a desired source and a second means capable of directing fluid containing particulates cleaned from filter media to a desired source, and   (e) means for recovering particulate free fluid from said inner chamber.   
     
     
       5. A method for filtering injection water prior to use in an offshore oil platform comprising filtering said water through an apparatus submerged in an ocean environment, said apparatus comprising (a) an inner chamber having an outer wall;   (b) an outer chamber surrounding said inner chamber and having an outer wall, the inner wall of said outer chamber being common with said outer wall of said inner chamber, both inner and outer walls being vertically aligned frusto-conical members set at opposing angles;   (c) means for retaining particulate filter media means in said outer chamber, said retaining means allowing fluid communication from said fluid through said retained particulate filter media means into said inner chamber, said means being the inner and outer chamber walls comprised of vertically aligned frusto-conical members set at opposing angles, and wherein both inner and outer chambers have fluid impermeable partitions at the upper and lower ends, and wherein output means are in fluid communication with the inner chamber;   (d) a cylindrical portion in axial alignment with said fluid impermeable end portions of the inner and outer chambers, said cylindrical portion penetrating the lower end of said inner chamber fluid impermeable housing, and the upper fluid impermeable ends of both the inner and outer chambers, said cylindrical portion surrounded by a housing affixed to the upper fluid impermeable end of said outer chamber, said housing containing a baffle situated over the upper end of the cylindrical portion;   (e) means for recovering particulate free fluid from said inner chamber; wherein   (f) fluid is forced through the filter by a pump on the clean water side of the filter, and wherein the pump is submerged in the fluid at a depth sufficient to provide a pressure head to the filter.